In recent years, with the advance of environmental technology, development of power generation devices (e.g., solar power generation devices) which pose less burden on the environment than conventional power generation methods has been actively conducted. Concurrently with the development of power generation devices, development of power storage devices has also been underway.
A lithium ion storage battery is one of power storage devices, for example, a lithium ion storage battery. Lithium ion storage batteries are widely prevalent because their energy density is high and they are suitable for miniaturization. As a material for a negative electrode of a lithium ion storage battery, a material to which lithium can be inserted and from which lithium can be removed is preferable, such as lithium nitride. When a lithium nitride is used as a negative electrode active material, charging and discharging can be performed at low voltage and extremely high specific capacitance can be obtained (see Patent Document 1, for example). Further, as one type of the power storage devices, development of capacitors has also been underway.